The present invention relates to the manufacture of objects. More particularly, the present invention provides a method for cleaning and packaging a sponge or porous polymeric product such as an ultra clean "scrubbing" brush or surface treatment device for the manufacture of integrated circuits, for example. Merely by way of example, the present invention is applied to a packaging method for a scrubbing device for the manufacture of integrated circuits. But it will be recognized that the invention has a wider range of applicability; it can also be applied to the manufacture of semiconductor substrates, hard disks, and the like.
In the manufacture of electronic devices such as integrated circuits, the presence of particulate contamination, trace metals, and mobile ions on a wafer is a serious problem. Particulate contamination can cause a wide variety of problems such as electrical "opens" or "shorts" in the integrated circuit. These opens and shorts often lead to reliability and functional problems in the affected integrated circuit. Mobile ion and trace metal contaminants can also lead to reliability and functional problems in the integrated circuit. The combination of these factors is the main source of lower device yields on a wafer, thereby increasing the cost of an average functional device on the wafer.
Chemical-mechanical polishing ("CMP") is a commonly used technique for planarizing a film on a wafer prior to subsequent processing of the wafer. CMP often requires introduction of a polishing slurry onto a surface of a film on the semiconductor wafer as the wafer is being mechanically polished against a rotating polishing pad. The slurries typically are water based and can contain fine abrasive particles such as silica, alumina, and other abrasive materials. After polishing is complete, the processed wafers must be cleaned to completely remove residual slurry and other residue from the polishing process to ready the surface for other processing steps such as etching, photolithography, and others.
To clean residual slurry material from the polished surface, cleaning brushes have been used. A cleaning brush of this type often comprises a member that is cylindrical in shape, which generally rotates along a center axis of the cylindrical shaped member. The cleaning brushes are also often made of a foam or porous polymeric material such as polyvinyl alcohol ("PVA"). A combination of rotational movement of the brush and force or pressure placed on the brush against the wafer causes residual slurry materials to be removed from the surface of the wafer. Unfortunately, it has been found that the brushes themselves often contain residual materials from the brush manufacturing process. These residual materials include, among others, residual particles and impurities such as ions and particulate contamination. Given that brushes received directly from a manufacturer are often "dirty" it is difficult to maintain the cleanliness of an integrated circuit manufacturing process by using such dirty brushes. Other impurities also may be introduced to the brush during the packaging process.
In some cases, conventional sponge or porous polymeric materials such as PVA attract microorganisms. More particular, microorganisms such as bacteria often introduce themselves on the wet surfaces and pores of the materials and reproduce at significant rates. These microorganisms contaminate the pores and surface area of the material. They also form particulate contamination, which should not be introduced in the manufacture of electronic devices such as integrated circuits. Furthermore, the microorganisms often degrade the quality of the material, which shortens it's life and resiliency. These and other microorganisms can also degrade the porous polymeric product material.
From the above, it is seen that an improved technique for maintaining cleanliness of a surface treatment device is highly desired.